1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive employing a disk with a pristine area for storing encrypted data accessible only by trusted devices or clients to facilitate secure network communications.
2. Description of the Prior Art
Cryptography for secure network communications is typically implemented by server and client computers attached to a network. With Internet communications, for example, cryptography is typically implemented by the server computers hosting secure web sites and the browser programs running on client computers. A secure communication protocol, such as the Secure Socket Layer (SSL), is used to transmit encrypted messages over public lines subject to inspection. If an encrypted message is intercepted while in transit, it is extremely difficult to decipher the message without the cryptographic key. For this reason, attackers are focusing their efforts on the computers which implement the cryptography algorithms in an attempt to glean information about the secret cryptographic keys used for the authentication and the encryption/decryption operations. The attacks may be physical using debuggers and logic analyzers, or they may be remote attacks using virus programs which invade the computer's operating system in order to obtain information concerning the cryptographic keys. A virus may, for example, be introduced remotely into a computer's operating system by attaching the virus to an email.
A paper by H. Gobioff, G. Gibson, and D. Tygar entitled “Security for Network Attached Storage Devices”, Oct. 23, 1997, School of Computer Science, Carnegie Mellon University, suggests to implement cryptography algorithms and secret keys in tamper resistant circuitry within a disk drive where it is less susceptible to probing and virus attacks. These types of disk drives, referred to as NASD disk drives, are intended to be attached directly to a network in order to avoid the overhead associated with an intervening file server. However, the above referenced paper does not disclose many details of implementation, particularly with respect to the authentication and encryption/decryption operations.
The Digital Transmission Content Specification or DTCP (available through the Internet at http://www.dtcp.com) discloses a cryptographic protocol for protecting audio/video (A/V) content from unauthorized copying as it traverses digital transmission mechanisms from device to device. Only compliant devices manufactured to support the DTCP protocol are capable of transmitting or receiving the protected A/V content. Each device is manufactured with a unique device ID and a public/private key pair which facilitate authentication and encryption/decryption of the A/V content. The DTCP specification suggests to store the private key in a way so as to prevent its disclosure, however, no specific means are disclosed for achieving this objective.
U.S. Pat. No. 5,931,947 discloses a network storage device for use in a secure array of such devices to support a distributed file system. Each device is an independent repository of remotely encrypted data to be accessed by authorized network clients. All encryption is done by the clients, rather than by the devices, and the encrypted data is stored in encrypted form. Each network storage device comprises an owner key used to generate authentication keys within the device for authenticating messages received from the clients. However, the keys used by the clients for encrypting data and generating the message authentication codes are generated external to the devices by a system administrator which is susceptible to attack. Further, the aforementioned patent does not disclose any details concerning the privacy of the owner key within each disk drive.
U.S. Pat. No. 5,687,237 discloses an encryption key management system for an integrated circuit which encrypts or decrypts data received from a microcontroller. The encryption and decryption operations are implemented using cryptographic keys stored in a non-volatile memory in encrypted form to protect against discovery. When needed to encrypt or decrypt data, the integrated circuit employs a secret internal key to decrypt the cryptographic keys stored in the non-volatile memory. Although storing the cryptographic keys in encrypted form protects against discovery, the aforementioned patent does not disclose any details concerning the authentication of users or devices requesting the encryption or decryption operations, nor does it disclose any details concerning the authentication of messages to verify that the messages have not been modified while in transit over public lines.
There is, therefore, the need to improve security in network communications, particularly with respect to probing attacks and virus attacks on computer operating systems.